Net energy dissipation in the tropical ocean and ENSO dynamics: modeling and theoretical study.

该项目力求估计热带太平洋从次年度到十年期的各种频率的净能量耗散，并探讨能量耗散如何影响厄尔尼诺/南方涛动现象的某些特征（周期、幅度和其他特性）。该项目有四个相互关联的组成部分：㈠计算与热带海洋大规模运动有关的净耗散率; ㈡系统地探讨控制这些耗散率的各种物理机制和模型参数化的作用; ㈢调查这些耗散率的不同数值如何影响最新的海洋-大气环流耦合模型对厄尔尼诺/南方涛动的模拟;（iv）使用中间耦合模式和理论考虑来阐明海洋能量耗散对厄尔尼诺性质的影响。本项目的最终任务是将能量学发展成为大气环流模式的标准诊断工具。知识价值：以前对ENSO的研究已经确定，在连续振荡中，拉尼娜对应于最大可用势能（APE）的状态，厄尔尼诺对应于最小能量的状态，因为APE是热带海洋温跃层斜率的量度。风对海洋所做的工作改变了海洋环流和浮力通量，从而产生或破坏APE。海洋中的能量耗散往往会减少这项工作。描述这种能量平衡的方程包含了系统的内在非线性动力学，从而为研究非线性振荡提供了一个方便的数学工具。在处理不同的模型时，能量学也提供了一个标准的统一方法。能量平衡将被用来研究模式的不同特征如何影响能量耗散率，另一方面，能量耗散的变化如何影响ENSO的性质。初步的理论结果支持耗散在控制或影响ENSO主要特征方面的重要性。最终，了解热带大尺度海洋运动的净能量耗散率将有助于解决热带气候理论中一个悬而未决的问题--ENSO循环是自我维持的还是阻尼的。更广泛的影响：该项目旨在探索控制厄尔尼诺/南方涛动动态的基本机制，如在自然界中观察到的和耦合气候模型模拟的。这将导致更好地模拟厄尔尼诺现象的大气环流模式（GCM）。模拟季节性和年际气候波动的耦合模式的发展正在迅速取得进展，但可靠预测厄尔尼诺现象的目标仍然遥不可及。该项目的一部分是通过评估耦合模式海洋部分的大尺度耗散特性，使耦合模式的开发更加系统化。将基于能量的方法转变为耦合大气环流模型的诊断工具，将有助于不同模型的比较，并有助于在现实模拟季节至年际气候变率方面取得进展。这将对气候预测有直接价值。 该项目的另一个重要部分是发展耶鲁大学的全球气候建模能力，这将使研究生和本科生受益，向他们介绍气候研究中的现代数值方法。这些建模能力将用于PI监督的学生的研究工作，以及本科生的高级项目，而通过本提案产生的研究成果将用于目前教授的课程或由主要研究者开发的课程。建模能力也将有助于与耶鲁大学其他教师的合作研究，并将提供给更广泛的耶鲁社区的教育用途。拟议的教育计划包括博士教育。气候动力学专业的学生

This project seeks to estimate net energy dissipation in the tropical Pacific ocean in a broad range of frequencies from sub-annual to decadal and to explore how energy dissipation affects certain characteristics of the El Nino / Southern Oscillation (ENSO) phenomenon (its period, amplitude and other properties). The project has four interconnected components: (i) to compute net dissipation rates associated with large-scale motion in the tropical ocean; (ii) to systematically explore the role of various physical mechanisms, and model parameterizations, that control those rates; (iii) to investigate how different values of those rates affect the simulation of ENSO by state-of-the-art coupled ocean-atmosphere general circulation models; and (iv) to use intermediate coupled models and theoretical considerations to elucidate the effect of oceanic energy dissipation on the properties of El Nino. The ultimate task of this project is to develop the energetics into a standard diagnostic tool for general circulation models.Intellectual Merit:Prior studies of ENSO have established that in a continual oscillation, La Nina corresponds to a state of maximum Available Potential Energy (APE), El Nino to a state of minimum energy, since APE is a measure of the thermocline slope in the tropical ocean. The work done on the ocean by the winds modifies the ocean circulation and buoyancy fluxes, thus creating or destroying APE. Energy dissipation in the ocean tends to reduce this work. The equation describing this energy balance encompasses intrinsic nonlinear dynamics of the system and thus provides a convenient mathematical tool for studying nonlinear oscillations. The energetics also offer a standard unifying approach when dealing with different models. The energy balance will be used to investigate how different characteristics of the models affect the energy dissipation rates, and, on the other hand, how changes in energy dissipation affect the properties of ENSO. Preliminary theoretical results support the importance of dissipation in controlling or influencing the main characteristics of ENSO. Ultimately, knowing the net energy dissipation rates associated with large-scale oceanic motion in the tropics will help to resolve an unsettled problem of the tropical climate theory - whether the ENSO cycle is self-sustained or damped. Broader Impacts:The project is aimed at exploring fundamental mechanisms that control the dynamics of ENSO as observed in nature and as simulated by coupled climate models. It will lead to a better simulation of El Nino by general circulation models (GCM). The development of coupled models for the simulation of seasonal and inter-annual climate fluctuations is progressing rapidly but the goal of a reliable El Nino prediction is still out of reach.. A part of this project is to make the development of coupled GCMs more systematic by evaluating large-scale dissipative properties of the oceanic component of coupled models. Transforming the energy-based approach into a diagnostic tool for coupled GCMs will facilitate comparison of different models and contribute to the progress towards a realistic simulation of seasonal-to-inter-annual climate variability. This will be of direct value for climate prediction. Another important part of this project is to develop global climate modeling capacities at Yale University, which will benefit both graduate and undergraduate students by introducing them to modern numerical approaches in climate research. These modeling capacities will be used in the research work of the students supervised by the PI, and in undergraduate senior projects, while research results originated through this proposal will be used in the classes currently taught or being developed by the Principal Investigator. The modeling capabilities will also contribute to collaborative research with other Yale faculty, and will be made available for educational use to the broader Yale community. The proposed educational plan includes the education of a Ph.D. student in climate dynamics.